Polyamide resins have good properties in terms of thermal resistance, wear resistance, chemical resistance and flame retardancy, and are thus used for a wide range of applications, such as electrical components, electronic components, automobile components, and the like.
With the trend of realizing excellent fuel efficiency, engine downsizing is in progress, and the number of automobiles having a turbocharger is increasing. Turbocharger parts are formed of a material having higher heat resistance because turbochargers are usually exposed to high temperature from engine output.
For example, parts in an under hood area (under-the-hood) are generally formed of polyamide resin compositions having good heat resistance, since the peripheral parts are exposed to high-temperature environments for a long time.
Generally, organic antioxidants such as phenol or phosphite antioxidants are broadly used to secure long-term thermal stability of polyamide resin compositions. However, the organic antioxidants have a limit in maintaining good physical properties of the polyamide resin compositions at high temperature for a long period of time.
In addition, a copper halide heat stabilizer, such as a CuI/KI mixture, known to exhibit good long-term thermal stability at high temperature as compared with organic antioxidants, can be used. However, copper can discolor or precipitate over time, thereby causing a problem in use for electrical, electronic, and automobile components.
Therefore, there is a need for polyamide resin compositions capable of maintaining high thermal stability despite exposure to high temperature for a long time in order to be used for peripheral parts of an automobile engine compartment.